Understanding of accretion process of atmospheres of short-period super-Earths

• Project/Area Number: 25400224
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: The University of Tokyo
• Principal Investigator: Ikoma Masahiro 東京大学, 大学院理学系研究科(理学部), 准教授 (80397025)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000); Fiscal Year 2015: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2014: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2013: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
• Keywords: 系外惑星 / 惑星形成 / 大気形成 / 大気起源

Outline of Final Research Achievements

A growing number of planets have been detected around stars other than the Sun. Those are called exoplanets. It has been recently revealed that the biggest population of exoplanets is planets of about 1-2 times the Earth's diameter, which are called super-Earths. According to their measured masses and diameters, the super-Earths are not a big version of the Earth, because many of them are low-density ones, relative to the Earth. This indicates that the super-Earths likely have thick atmospheres. It was poorly known how super-Earths obtain such thick atmospheres. In this research project, I have investigated theoretically the accumulation process of the atmosphere on super-Earths embedded in protoplanetary disks where planet formation occurs. Then, I have quantified the conditions required for the formation of such thick atmospheres of super-Earths.

Research Products

• [Journal Article] Formation and Evolution of Protoatmospheres (2016)
  • Author(s): Massol, H., Hamano K., Tian F., Ikoma M., Abe, Y.., Chassefiere E., Davaille A., Genda H., Gudel M., Hori Y., Leblanc F., Marcq E., Sarda P., Shematovich, V. I., Stokl, A. and Lammer H
  • Journal Title: Space Science Reviews Volume: Volume 205, Issue 1-4, Issue: 1-4 Pages: 153-211
  • DOI: 10.1007/s11214-016-0280-1
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Demonstrating High-precision, Multiband Transit Photometry with MuSCAT: A Case for HAT-P-14b (2016)
  • Author(s): Fukui, A., Narita, N., Kawashima, Y., Kusakabe, N., Onitsuka, M., Ryu, T., Ikoma, M., Yanagisawa, K., Izumiura, H.
  • Journal Title: The Astrophysical Journal Volume: 819 Issue: 1 Pages: 27-37
  • DOI: 10.3847/0004-637x/819/1/27
  • Peer Reviewed / Open Access
• [Journal Article] Critical Core Mass for Enriched Envelopes: The Role of H2O Condensation (2015)
  • Author(s): Venturini, J., Alibert, Y., Benz, W., Ikoma, M.
  • Journal Title: Astronomy & Astrophysics Volume: 576 Pages: A114-A114
  • DOI: 10.1051/0004-6361/201424008
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Theoretical Emission Spectra of Atmospheres of Hot Rocky Super-Earths (2015)
  • Author(s): Ito, Y., Ikoma, M., Kawahara, H., Nagahara, H., Kawashima, Y., and Nakamoto, T.
  • Journal Title: The Astrophysical Journal Volume: 801 Issue: 2 Pages: 144-144
  • DOI: 10.1088/0004-637x/801/2/144
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Critical core mass for enriched envelopes: the role of H2O condensation (2015)
  • Author(s): VENTURINI Julia, ALIBERT Yann, BENZ Willy, IKOMA Masahiro
  • Journal Title: Astronomy & Astrophysics Volume: 印刷中
  • Acknowledgement Compliant
• [Journal Article] Multi-band, Multi-epoch Observations of the Transiting Warm Jupiter WASP-80b (2014)
  • Author(s): Akihiko Fukui, Yui Kawashima, Masahiro Ikoma, Norio Narita, Masahiro Onitsuka, Yoshifusa Ita, Hiroki Onozato, Shogo Nishiyama, Haruka Baba, Tsuguru Ryu, Teruyuki Hirano, et al.
  • Journal Title: The Astrophysical Journal Volume: 790 Issue: 2 Pages: 108-108
  • DOI: 10.1088/0004-637x/790/2/108
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Impact of Photoevaporative Mass Loss on Masses and Radii of Water-rich Sub/super-Earths (2014)
  • Author(s): Kurosaki, K., Ikoma, M., Hori, Y.
  • Journal Title: Astronomy & Astrophysics Volume: Vol.562 Pages: A80-A80
  • DOI: 10.1051/0004-6361/201322258
  • Peer Reviewed
• [Journal Article] Starspots-Transit Depth Relation of the Evaporating Planet Candidate KIC 12557548b (2013)
  • Author(s): Hajime Kawahara, Teruyuki Hirano, Kenji Kurosaki, Yuichi Ito, Masahiro Ikoma
  • Journal Title: The Astrophysical Journal Letters Volume: 776 Issue: 1 Pages: L6-L6
  • DOI: 10.1088/2041-8205/776/1/l6
  • Peer Reviewed
• [Journal Article] Multi-color Transit Photometry of GJ 1214b through BJHK sBands and a Long-term Monitoring of the Stellar Variability of GJ 1214 (2013)
  • Author(s): Narita, Norio, Fukui, Akihiko, Ikoma, Masahiro, Hori, Yasunori, Kurosaki, Kenji, Kawashima, Yui, Nagayama, Takahiro, Onitsuka, Masahiro, Sukom, Amnart, Nakajima, Yasushi, Tamura, Motohide, Kuroda, Daisuke, Yanagisawa, Kenshi, Hirano, Teruyuki, Kawauchi, Kiyoe, Kuzuhara, Masayuki, Ohnuki, Hiroshi, Suenaga, Takuya, Takahashi, Yasuhiro H., et al.
  • Journal Title: The Astrophysical Journal Volume: 773 Issue: 2 Pages: 144-153
  • DOI: 10.1088/0004-637x/773/2/144
  • Peer Reviewed
• [Journal Article] Optical-to-near-infrared Simultaneous Observations for the Hot Uranus GJ3470b : A Hint of a Cloud-free Atmosphere (2013)
  • Author(s): Fukui, Akihiko, Narita, Norio, Kurosaki, Kenji, Ikoma, Masahiro, Yanagisawa, Kenshi, Kuroda, Daisuke, Shimizu, Yasuhiro, Takahashi, Yashiro H., et al.
  • Journal Title: The Astrophysical Journal Volume: 770 Issue: 2 Pages: 95-107
  • DOI: 10.1088/0004-637x/770/2/95
  • Peer Reviewed
• [Journal Article] IRSF SIRIUS JHKs Simultaneous Transit Photometry of GJ 1214b (2013)
  • Author(s): Narita, N., Nagayama, T., Suenaga, T., Fukui, A., Ikoma, M., Nakajima, Y., Nishiyama, S., Tamura, M.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 65 Issue: 2 Pages: 27-27
  • DOI: 10.1093/pasj/65.2.27
  • Peer Reviewed
• [Presentation] Formation and evolution of giant planets with snowy envelopes (2017)
  • Author(s): Ikoma, M.
  • Organizer: Planet2 Symposium 2017: Origin and diversity of planetary systems from the microscope to the telescope
  • Place of Presentation: Villefranche-sur-Mer, France
  • Year and Date: 2017-02-21
  • Int'l Joint Research
• [Presentation] Effects of snow on giant planet formation (2016)
  • Author(s): Ikoma, M.
  • Organizer: International Workshop on "Exoplanets and Disks: Their Formation and Diversity III"
  • Place of Presentation: ホテル日航八重山（沖縄県石垣市）
  • Year and Date: 2016-02-22
  • Int'l Joint Research
• [Presentation] Role of Magma Ocean and Primitive Atmospheres for the Hydration of Planetary Embryos. (2016)
  • Author(s): Ikoma, M.
  • Organizer: The Delivery of Water to Protoplanets, Planets and Satellites
  • Place of Presentation: Bern, Switzerland
  • Year and Date: 2016-01-13
  • Int'l Joint Research / Invited
• [Presentation] 見えはじめた系外惑星の大気 (2015)
  • Author(s): 生駒 大洋
  • Organizer: 第138回地球電磁気・地球惑星圏学会 (SGEPSS) 秋季講演会
  • Place of Presentation: 東京大学（東京都文京区）
  • Year and Date: 2015-11-02
  • Invited
• [Presentation] What can we learn from atmospheres of transiting low-mass exoplanets as a stepping stone towards habitable planets? (2015)
  • Author(s): Ikoma, M.
  • Organizer: Pathways 2015: Pathways towards habitable planets.
  • Place of Presentation: Bern, Switzerland
  • Year and Date: 2015-07-15
  • Int'l Joint Research / Invited
• [Presentation] Theoretical perspective on super-Earths and mini-Neptunes with a focus on the origins and compositions of short-period exoplanets. (2015)
  • Author(s): Ikoma, M.
  • Organizer: 31st int'l colloquium of the Institut D'Astrophysique de Paris From super-Earths to brown dwarfs: who's who?
  • Place of Presentation: Paris, France
  • Year and Date: 2015-06-30
  • Int'l Joint Research / Invited
• [Presentation] Bulk and atmospheric composition of transiting low-mass exoplanets and their origins (2014)
  • Author(s): IKOMA Masahiro
  • Organizer: The 2014 German-Japanese meeting on Exoplanets and Their Formation
  • Place of Presentation: ハイデルベルグ（ドイツ）
  • Year and Date: 2014-11-06
  • Invited
• [Presentation] Formation of the nebular-captured protoatmosphere (2014)
  • Author(s): IKOMA Masahiro
  • Organizer: Workshop on the Disk in Relation to the Formation of Planets and Their Protoatmospheres
  • Place of Presentation: 北京（中国）
  • Year and Date: 2014-08-27
  • Invited
• [Presentation] Accumulation and loss of hydrogen-rich atmospheres of exo-Earths (2014)
  • Author(s): IKOMA Masahiro
  • Organizer: Origins 2014 (2nd ISSOL and IAU C51 Joint International Conference
  • Place of Presentation: 奈良春日野国際フォーラム（奈良県）
  • Year and Date: 2014-07-07
• [Presentation] 太陽系内の巨大惑星の内部構造 (2014)
  • Author(s): 生駒 大洋
  • Organizer: 系外惑星大気WS2014
  • Place of Presentation: 国立天文台三鷹
  • Invited
• [Presentation] Composition and origin of short-period low-mass planets: The importance of observation of their atmospheres (2013)
  • Author(s): 生駒 大洋
  • Organizer: Exoplanets and Disk: Their Formation and Diversity II
  • Place of Presentation: Keauhou Kona, Hawaii
  • Invited
• [Presentation] Current understanding of the interiors and origins of large-sized planets in the solar system and beyond (2013)
  • Author(s): 生駒 大洋
  • Organizer: SEDI Pre-Symposium 2013
  • Place of Presentation: 湘南国際村センター
  • Invited
• [Presentation] 木星から見えてくる太陽系らしさの起源 (2013)
  • Author(s): 生駒 大洋
  • Organizer: 第４回深宇宙探査学シンポジウム
  • Place of Presentation: 東京大学
  • Invited
• [Presentation] 短周期低質量系外惑星の内部組成と起源～大気スペクトル観測の重要性～ (2013)
  • Author(s): 生駒 大洋
  • Organizer: 日本惑星科学会秋季講演会2013
  • Place of Presentation: 沖縄県石垣島市民会館
• [Book] 系外惑星の事典 (2016)
  • Author(s): 井田茂・田村元秀・生駒大洋・関根康人
  • Total Pages: 364
  • Publisher: 朝倉書店